This invention relates generally to apparatus for obtaining flow of water for underground wells, and more particularly to retrievable apparatus enabling pumping of water upwardly in a well and then laterally into underground pipes.
In the past, plastic pitless spools and housings have experienced difficulty when metal pipe was threaded into the spool or housing. Both male and female pipe threads are tapered so that when a metal pipe thread is secured into a plastic female pipe thread, and over tightened, the plastic will split. When the plastic spool splits, the entire drop pipe and pump would fall into the well. Also when the housing splits, the waterline would leak into the soil and then contaminate the well.
Manufacturers have tried unsuccessfully to “educate” the plumber to prevent them from over tightening the metal pipe. They have added fiberglass for strength to the plastic resin, molded metal rings into the plastic near the threads and even added an external banding around the outside of the plastic threaded area, all in an effort to prevent the plastic from splitting. The inability to correct this problem has forced manufacturers to withdraw their plastic pitless spools and housings from the market place.
There is need for simplifying improvements in apparatus referred to above, and particularly facilitating ease of retrieval of the underground pump, and without interference with sideward duct connection to lateral underground pipe which enables water delivery without freezing in winter. No apparatus of which I am aware embodies the improvements in construction, functioning and results, as are now provided by the present invention.
After much testing and research, it has been found that by placing a stop or shoulder at the base of the plastic threads it automatically prevents splitting of the plastic by limiting the travel of the metal pipe. A second solution to the problem is to mold the plastic threads as a male pipe thread. This forces a plumber to use a metal coupling before securing the metal pipe. The metal coupling, which has a female pipe thread, will have a clamping force on the molded plastic male pipe thread, thus preventing the plastic from splitting.